This invention relates to communication bandwidth control.
The progress in speed of the Internet access has propelled the growth of cloud computing. Cloud computing exchanges massive data between data centers and users via the Internet. In the case where a data center is located overseas, data is exchanged through a long-distance network. The long-distance network is called a Wide Area Network (WAN).
The Internet typically uses TCP (Transmission Control Protocol) communication. A feature of the TCP communication is that a receiver computer that has received data sends an acknowledgment (ACK) of the data to the sender computer. Furthermore, in the TCP communication, the receiver computer notifies the sender computer of a numerical value called receive window size (RWIN) together with the ACK.
The sender computer sends data so that the data size called inflight, which is the size of data that has been sent but not acknowledged, will not exceed the RWIN. Accordingly, the inflight is limited up to the RWIN during a Round Trip Time (RTT), which is the time since sending data until receiving a response. For this reason, the transmission bandwidth is limited to the RWIN/RTT at maximum.
The background art of this technology include JP 2012-95190 A, which discloses: a control unit that determines whether a channel with respect to the reception side communication device is in a broad band and high delay circumstance, changes a first state where the transmission window size is a first window size which is not larger than the reception window size to a second state where the transmission window size is a second window size which is larger than the reception window size when the channel is determined to be in the broad band and high delay circumstance, and transmits the packet of the transmission amount larger than the reception window size in the second state.